1. Field of the Invention
This invention generally relates to a method and apparatus for detecting abnormal conditions or faults of a switch gear, for instance a gas insulated switch gear from outside thereof, and more particularly to a method and apparatus for detecting abnormal mechanical conditions relating to operation of the switch gear.
About 90% of the faults of a switch gear are mechanical faults such as leakage of air, gas or oil, fracture, failure or improper operation of the switch gear itself or it's operating mechanism.
Leakage of air, gas or oil can be detected with a pressure relay to produce an alarm signal whereas an inoperable state or improper operation can not be detected until such faults actually occur. The reason is, in most cases, various elements of the circuit breaker do not move during steady state after closing, but the elements move as desired only when a fault occurs on a power circuit.
The method and apparatus for detecting in advance abnormal conditions of switch gear is disclosed in copending application Ser. No. 246,061, filed Mar. 20, 1981, for A. Aoyagi and S. Ikeda. With the recent increase in power demand, the operating voltage and capacity of the switch gear increases year by year and any fault or abnormal condition thereof results in even more serious problems.